笔记记录之reactnative：can't find entry file index.ios.js in any of the roots
有时不小心操作了什么就会出现这个错误， some解决方法：
When I run the packenger in another terminal first from the root folder via
npm run start
and than
react-native run-ios
The problem goes away. Still, react-native run-ios seems not to start the packager properly.